I (Mexican, with Mexican wife) lived in Germany for 4 years while doing research in a Leibniz Institute. At some point my wife and I talked with a German colleague about how difficult it was for us to make acquaintances or friends while living there.
This colleague mentioned that it was the same for her, who was German but from a different part of Germany (like, we were in the East part of Germany and she was from the Northern part). She mentioned that Germans for the most part make their friends groups in the first ~18 years of their lives, and afterwards it is difficult to make friends.
Also reminds me of a time I was in the UK, walking with a German girl, near a train station. We saw a person who looked pretty lost (I think he had luggage and was looking at a wall map... al in all he looked confused). I approached this guy and asked him whether he needed help. He replied with a German accent, and he was indeed lost and was looking for some place. I proceeded to give him instructions on how to get to where he was going.
During all this time, my German friend was a bit further away from us. After I finished helping the guy she found it amusing how I approached the person and talked to him "out of nowhere". She told me that in Germany you don't normally approach people that you don't know like that. I asked her, "then how do you make new friends?" to what she responded that maybe only by introduction form a third party.
Anglo Saxon culture was quite a strong culture shock for me as a Latino.